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United States Patent |
5,340,159
|
Mowry, Jr.
|
August 23, 1994
|
Varying tone security document
Abstract
An improved security document according to the present invention includes a
substrate having a surface for carrying indicia. The document has
background printed matter, consisting of a pattern of elements of a first
size and frequency, printed at a first density on the surface. The
document further has a cancellation term, consisting of a pattern of
elements of a second size and frequency, printed at a second density on
the surface. Elements of one of the first size or the second size are
sufficiently small such that they are not reproduced by a color copier at
a particular copier setting, and elements of the other of the first size
or the second size are sufficiently large such that they are reproduced by
the color copier at the particular copier setting. As a result, a copy of
the security document made on a color copier displays the cancellation
term. At least a portion of the security document surface is divisible
into a plurality of bands extending across the surface. The sizes of the
elements and the density of the background printed matter and the
cancellation term vary together across the bands in a direction generally
normal to the bands. As an alternative, the frequencies of the elements
may vary across the bands such that the density of the background printed
matter and the density of the cancellation term are changed. Such a
document may be printed with different colors of ink on different portions
of the document, and with the bands in which a color transition occurs
being printed with two colors of ink at differing screen angles.
Inventors:
|
Mowry, Jr.; William H. (Dayton, OH)
|
Assignee:
|
The Standard Register Company (Dayton, OH)
|
Appl. No.:
|
024666 |
Filed:
|
March 1, 1993 |
Current U.S. Class: |
283/93; 283/94; 283/95; 283/902 |
Intern'l Class: |
B42D 015/00 |
Field of Search: |
283/93,94,95,902
|
References Cited
U.S. Patent Documents
3675948 | Jul., 1972 | Wicker.
| |
3784289 | Jan., 1974 | Wicker.
| |
4168088 | Sep., 1979 | Somlyody.
| |
4210346 | Jul., 1980 | Mowry, Jr. et al.
| |
4227719 | Oct., 1980 | McElligott et al.
| |
4227720 | Oct., 1980 | Mowry, Jr. et al.
| |
4265469 | May., 1981 | Mowry, Jr. et al.
| |
4310180 | Jan., 1982 | Mowry, Jr. et al.
| |
4341404 | Jul., 1982 | Mowry, Jr. et al.
| |
4351547 | Sep., 1982 | Brooks, II.
| |
4360548 | Nov., 1982 | Skees et al.
| |
4420175 | Dec., 1985 | Mowry, Jr.
| |
4579370 | Apr., 1986 | Corwin et al.
| |
4582346 | Apr., 1986 | Caprio et al.
| |
4662651 | May., 1987 | Mowry, Jr.
| |
4733887 | Mar., 1988 | Mowry, Jr.
| |
5018767 | May., 1991 | Wicker.
| |
5074956 | Dec., 1991 | Castagnoli.
| |
Foreign Patent Documents |
2217258 | Oct., 1989 | GB | 283/93.
|
Primary Examiner: Rosenbaum; Mark
Assistant Examiner: Han; Frances
Attorney, Agent or Firm: Killworth, Gottman, Hagan & Schaeff
Parent Case Text
This is a continuation-in-part of U.S. patent application Ser. No.
07/729,363, filed Jul. 12, 1991 now U.S. Pat. No. 5,197,765 entitled
VARYING TONE SECURITY DOCUMENT.
Claims
What is claimed is:
1. An improved security document, comprising:
a substrate having a surface for carrying indicia;
background printed matter on said surface, said background printed matter
consisting of a pattern of elements of a first size and a first frequency
such that said background printed matter is printed at a first density
perceived by an observer as a first tone; and
a cancellation term printed on said surface, said cancellation term
consisting of a pattern of elements of a second size and a second
frequency such that said cancellation term is printed at a second density
perceived by an observer as a second tone, elements of one of said first
size or said second size being sufficiently small such that they are not
reproduced by a color copier at a particular copier setting, and elements
of the other of said first size or said second size being sufficiently
large such that they are reproduced by said color copier at said
particular copier setting, so that a copy of said security document made
on a color copier displays said cancellation term, at least a portion of
said security document surface being divisible into a plurality of bands
extending across said surface, the sizes of said elements of said first
and second sizes varying across each of said bands and the frequencies of
said elements of said first and second frequency varying across each of
said bands such that the density of said background printed matter and the
density of said cancellation term vary together across each of said bands
on said surface, thereby impeding copying said security document without
said cancellation term being apparent on at least some portion of the copy
of said security document.
2. The improved security document of claim 1 in which the density of said
background printed matter and the density of said cancellation term vary
together linearly across at least some of said plurality of bands.
3. The improved security document of claim 1 in which the tone of each
portion of the surface printed with those elements which are sufficiently
large such that they are reproduced by said color copier at said
particular copier setting is greater than the tone of adjacent portions of
the surface printed with elements which are sufficiently small such that
they are not reproduced by a color copier at a particular copier setting.
4. The improved security document of claim 1 further comprising a
camouflage pattern on said surface to disguise said cancellation term.
5. The improved security document of claim 4 in which said camouflage
pattern is defined by the absence of said elements of said first and
second sizes.
6. The improved security document of claim 4 in which said camouflage
pattern is defined by the presence of further elements.
7. The improved security document of claim 1 in which said cancellation
term consists of a plurality of letters, each of which is approximately
two bands in height.
8. The improved security document of claim 1 in which the density of said
background printed matter and the density of said cancellation term vary
together in a non-linear fashion across at least some of said plurality of
bands.
9. The improved security document of claim 8 in which the density of said
background printed matter and the density of said cancellation term vary
together in a logarithmic manner across at least some of said plurality of
bands.
10. The improved security document of claim 1 in which the density of said
background printed matter and the density of said cancellation term along
each edge of each band are substantially the same as the density of said
background printed matter and the density of said cancellation term along
the edge of the adjacent band, respectively.
11. The improved security document of claim 1 in which a plurality of
cancellation terms are printed on said surface, at least some of said
plurality of cancellation terms being printed over more than one of said
plurality of bands.
12. The improved security document of claim 11 in which said plurality of
cancellation terms and said plurality of bands vary in height.
13. The improved security document of claim 1 in which the color of said
background printed matter and the color of said cancellation term vary
together over said surface.
14. The improved security document of claim 13 in which the upper portion
of said security document is printed with a first color and the lower
portion of the security document is printed with a second color, and in
which the color transition area in the central portion of the security
document is printed in both colors at a relatively low density.
15. The improved security document of claim 14 in which the screen angle of
the pattern of elements in said central portion printed with said first
color differs from the screen angle of the pattern or elements in said
central portion printed with said second color, thereby facilitating a
smooth transition between colors.
16. The improved security document of claim 1 in which the tone of each
portion of the surface printed with those elements which are sufficiently
large such that they are reproduced by said color copier at said
particular copier setting is substantially the same as the tone of
adjacent portions of the surface printed with elements which are
sufficiently small such that they are not reproduced by a color copier at
a particular copier setting.
17. An improved security document, comprising:
a substrate having a surface for carrying indicia;
background printed matter on said surface, said background printed matter
consisting of a pattern of elements of a first size and a first frequency
such that said background printed matter is printed at a first density
perceived by an observer as a first tone; and
a cancellation term printed on said surface, said cancellation term
consisting of a pattern of elements of a second size and a second
frequency such that said cancellation term is printed at a second density
perceived by an observer as a second tone, elements of one of said first
size or said second size being sufficiently small such that they are not
reproduced by a color copier at a particular copier setting, and elements
of the other of said first size or said second size being sufficiently
large such that they are reproduced by said color copier at said
particular copier setting, so that a copy of said security document made
on a color copier displays said cancellation term, at least a portion of
said security document surface being divisible into a plurality of bands
extending across said surface, the sizes of said elements of said first
and second sizes varying across each of said bands such that the density
of said background printed matter and the density of said cancellation
term vary together across each of said bands on said surface, thereby
impeding copying said security document without said cancellation term
being apparent on at least some portion of the copy of said security
document.
18. The improved security document of claim 17 in which the density of said
background printed matter and the density of said cancellation term vary
together linearly across at least some of said plurality of bands.
19. The improved security document of claim 17 in which the tone of each
portion of the surface printed with those elements which are sufficiently
large such that they are reproduced by said color copier at said
particular copier setting is greater than the tone of adjacent portions of
the surface printed with elements which are sufficiently small such that
they are not reproduced by a color copier at a particular copier setting.
20. The improved security document of claim 17 further comprising a
camouflage pattern on said surface to disguise said cancellation term.
21. The improved security document of claim 20 in which said camouflage
pattern is defined by the absence of said elements of said first and
second sizes.
22. The improved security document of claim 20 in which said camouflage
pattern is defined by the presence of further elements.
23. The improved security document of claim 17 in which said cancellation
term consists of a plurality of letters, each of which is approximately
two bands in height.
24. The improved security document of claim 17 in which the density of said
background printed matter and the density of said cancellation term vary
together in a non-linear fashion across at least some of said plurality of
bands.
25. The improved security document of claim 24 in which the density of said
background printed matter and the density of said cancellation term vary
together in a logarithmic manner across at least some of said plurality of
bands.
26. The improved security document of claim 17 in which the density of said
background printed matter and the density of said cancellation term along
each edge of each band are substantially the same as the density of said
background printed matter and the density of said cancellation term along
the edge of the adjacent band, respectively.
27. The improved security document of claim 17 in which a plurality of
cancellation terms are printed on said surface, at least some of said
plurality of cancellation terms being printed over more than one of said
plurality of bands.
28. The improved security document of claim 27 in which said plurality of
cancellation terms and said plurality of bands vary in height.
29. The improved security document of claim 17 in which the color of said
background printed matter and the color of said cancellation term vary
together over said surface.
30. The improved security document of claim 29 in which the upper portion
of said security document is printed with a first color and the lower
portion of the security document is printed with a second color, and in
which the color transition area in the central portion of the security
document is printed in both colors at a relatively low density.
31. The improved security document of claim 30 in which the screen angle of
the pattern of elements in said central portion printed with said first
color differs from the screen angle of the pattern of elements in said
central portion printed with said second color, thereby facilitating a
smooth transition between colors.
32. The improved security document of claim 17 in which the tone of each
portion of the surface printed with those elements which are sufficiently
large such that they are reproduced by said color copier at said
particular copier setting is substantially the same as the tone of
adjacent portions of the surface printed with elements which are
sufficiently small such that they are not reproduced by a color copier at
a particular copier setting.
33. An improved security document, comprising:
a substrate having a surface for carrying indicia;
background printed matter on said surface, said background printed matter
consisting of a pattern of elements of a first size and a first frequency,
such that said background printed matter is printed at a first density
perceived by an observer as a first tone; and
a cancellation term printed on said surface, said cancellation term
consisting of a pattern of elements of a second size and a second
frequency such that said cancellation term is printed at a second density
perceived by an observer as a second tone, elements of one of said first
size or said second size being sufficiently small such that they are not
reproduced by a color copier at a particular copier setting, and elements
of the other of said first size or said second size being sufficiently
large such that they are reproduced by said color copier at said
particular copier setting, so that a copy of said security document made
on a color copier displays said cancellation term, at least a portion of
said security document surface being divisible into a plurality of bands
extending across said surface, and the frequencies of said elements of
said first and said second frequency varying across each of said bands
such that the density of said background printed matter and the density of
said cancellation term vary together across each of said bands on said
surface, thereby impeding copying said security document without said
cancellation term being apparent on at least some portion of the copy of
said security document.
34. The improved security document of claim 33 in which the density of said
background printed matter and the density of said cancellation term vary
together linearly across at least some of said plurality of bands.
35. The improved security document of claim 33 in which the tone of each
portion of the surface printed with those elements which are sufficiently
large such that they are reproduced by said color copier at said
particular copier setting is greater than the tone of adjacent portions of
the surface printed with elements which are sufficiently small such that
they are not reproduced by a color copier at a particular copier setting.
36. The improved security document of claim 33 further comprising a
camouflage pattern on said surface to disguise said cancellation term.
37. The improved security document of claim 36 in which said camouflage
pattern is defined by the absence of said elements of said first and
second sizes.
38. The improved security document of claim 36 in which said camouflage
pattern is defined by the presence of further elements.
39. The improved security document of claim 33 in which said cancellation
term consists of a plurality of letters, each of which is approximately
two bands in height.
40. The improved security document of claim 33 in which the density of said
background printed matter and the density of said cancellation term vary
together in a non-linear fashion across at least some of said bands.
41. The improved security document of claim 40 in which the density of said
background printed matter and the density of said cancellation term vary
together in a logarithmic manner across at least some of said plurality of
bands.
42. The improved security document of claim 3 in which the density of said
background printed matter and the density of said cancellation term along
each edge of each band are substantially the same as the density of said
background printed matter and the density of said cancellation term along
the edge of the adjacent band, respectively.
43. The improved security document of claim 33 in which a plurality of
cancellation terms are printed on said surface, at least some of said
plurality of cancellation terms being printed over more than one of said
plurality of bands.
44. The improved security document of claim 43 in which said plurality of
cancellation terms and said plurality of bands vary in height.
45. The improved security document of claim 33 in which the color of said
background printed matter and the color of said cancellation term vary
together over said surface.
46. The improved security document of claim 45 in which the upper portion
of said security document is printed with a first color and the lower
portion of the security document is printed with a second color, and in
which the color transition area in the central portion of the security
document is printed in both colors at a relatively low density.
47. The improved security document of claim 46 in which the screen angle of
the pattern of elements in said central portion printed with said first
color differs from the screen angle of the pattern of elements in said
central portion printed with said second color, thereby facilitating a
smooth transition between colors.
48. The improved security document of claim 33 in which the tone of each
portion of the surface printed with those elements which are sufficiently
large such that they are reproduced by said color copier at said
particular copier setting is substantially the same as the tone of
adjacent portions of the surface printed with elements which are
sufficiently small such that they are not reproduced by a color copier at
a particular copier setting.
Description
BACKGROUND OF THE INVENTION
The importance of making various types of documents safe from nefarious
duplication is readily apparent. The development of the color copier has
resulted in significant concern in this regard. The quality of color
reproductions that can be made with a color copier has become so good that
it may be very difficult to distinguish the original documents from the
color reproductions. Even if a reproduction is not an exact copy, the
reproduction often appears reasonably authentic in the absence of the
original for comparison purposes. As a consequence, there has been concern
that color copiers could be used to reproduce security documents, such as
checks, stock certificates, automobile title instruments, and other
documents of value, for illegal purposes. This concern has been heightened
with the advent of desk top publishing software and hardware, including
personal computers and scanners. Such desk top publishing systems allow
sophisticated image processing and printing not previously generally
available.
Many techniques have been developed to prevent improper reproduction of
security documents. One of the most successful is the use of a hidden
warning message which is readily apparent on reproduced copies of a
document, but which is invisible, or nearly so, on the original document.
Examples of this technique are shown in U.S. Pat. Nos. 4,227,720 and
4,310,180. A single tone warning phrase and a single tone background
pattern are used. Tone refers to the visual effect produced by solid ink
coverage or by halftone dots, bars, or marks which cover a portion of a
printed area and which usually have a frequency that is measured in dots,
lines, or marks per inch. Halftone dots, bars, or marks may be more or
less uniformly distributed over an area to produce the visual effect,
i.e., less than full tone, of a lighter overall color with the use of a
darker color ink printed at less than full area coverage. The warning
phrase and background pattern area tones are of different frequency and
are made up of dots, bars, or marks of differing size but they are
selected to provide similar appearance to the eye of a casual observer. A
less than full tone effect may also be produced by full area coverage of a
paler color of ink than the darker color of ink used for the halftone
dots, bars, or marks.
Because the tone of the warning phrase and the tone of the background
pattern are selected to be the same, these two areas have much the same
visual impact on an observer of the original document, and the warning
phrase is not readily perceived. The optics of color copiers have
typically been unable to reproduce relatively small halftone dots, lines
or other elements. As a consequence, reproduced copies of the original
document will have a noticeable warning phrase.
A camouflage pattern is sometimes utilized to obscure the warning phrase
further. The camouflage pattern may be defined by areas in which the dots,
bars, or marks have been deleted from both the warning phrase and the
background pattern. The camouflage pattern may also be defined by a
pattern of dots, bars, or marks which are smaller than or larger than
those used in the background pattern and the warning phrase, or by areas
of complete coverage of a paler ink.
In recent years, color copiers have been improved substantially. These new
color copiers have made the above technique less effective in protecting
documents. By manipulating the control settings on such copiers, copies
can be made of such documents in which the warning phrase does not appear
on reproductions when some of the most commonly used frequency and size
combinations are used. Furthermore, desk top publishing systems now
available in conjunction with laser printers, offer additional
possibilities for unauthorized copying. Therefore, it is clear that
improvements in this technique are desirable.
One such improvement is shown in U.S. Pat. No. 4,351,547, which also
utilizes a single tone background and a single tone cancellation phrase.
In this improved technique, the warning phrase is not defined by dots or
elements of the same size and frequency. Instead, the warning phrase is
defined by an alternating dot pattern which includes large dots of lower
frequency than the background tone, and small dots located in exact
registry with the large dots.
U.S. Pat. No. 4,579,370 represents another improvement in the use of a
hidden warning phrase. The background and warning phrase are each made up
of halftone dots of two pairs of dot sizes. For example, the background
might be made with about 50% of 130 lines per inch 0.005 inch diameter,
and the balance of 130 lines per inch, 0.006 inch diameter; the
cancellation term might be made with about 50% of the dots of 65 lines per
inch, 0.010 inch diameter and the balance of 65 lines per inch, 0.012 inch
diameter. This provides additional protection for documents against
improper copying.
These methods have generally been successful in protecting documents at
most copier settings. However, by adjusting the settings for sharpness and
lightness/darkness it has still been possible on some copiers for a
skilled individual to produce a copy in which the warning phrase is not
visible.
Therefore, there remains a need in the art for a security document which
provides improved protection against copying over a wide range of copier
settings, or against manipulation using desk top publishing systems.
SUMMARY OF THE INVENTION
This need is met by an improved security document according to the present
invention including a substrate having a surface for carrying indicia. The
document includes background printed matter on the surface, the background
printed matter consisting of a pattern of elements of a first size and a
first frequency such that the background printed matter is printed at a
first density perceived by an observer as a first tone. The document
further includes a cancellation term printed on the surface, the
cancellation term consisting of a pattern of elements of a second size and
a second frequency such that the cancellation term is printed at a second
density perceived by an observer as a second tone. Elements of one of the
first size or the second size are sufficiently small such that they are
not reproduced by a color copier at a particular copier setting, and
elements of the other of the first size or the second size are
sufficiently large such that they are reproduced by the color copier at
the particular copier setting. As a result, a copy of the security
document made on a color copier displays the cancellation term. At least a
portion of the security document surface is divisible into a plurality of
bands extending across the surface. The sizes of the elements of the first
and second sizes vary across each of the bands such that the density of
the background printed matter and the density of the cancellation term
vary together across each of the bands on the surface, preferably in a
direction generally normal to the bands. By this arrangement, copying the
security document without the cancellation term being apparent on at least
some portion of the copy is impeded.
As an alternative, the frequencies of the elements of the first and the
second frequency may vary across each of the bands such that the density
of the background printed matter and the density of the cancellation term
vary together across each of the bands on the surface in a direction
generally normal to the bands. As a further alternative, the sizes of the
elements of the first and second sizes may vary across each of the bands
and the frequencies of the elements of the first and second frequency may
vary across each of the bands such that the density of the background
printed matter and the density of the cancellation term vary together
across each of the bands on the surface in a direction generally normal to
the bands.
The density of the background printed matter and the density of the
cancellation term may vary together linearly across each of the plurality
of bands. The tone of each portion of the surface printed with those
elements which are sufficiently large such that they are reproduced by the
color copier at the particular copier setting may be greater than the tone
of adjacent portions of the surface printed with elements which are
sufficiently small such that they are not reproduced by a color copier at
a particular copier setting. Alternatively, these tones may be
substantially the same.
A camouflage pattern may be provided on the surface to disguise the
cancellation term. The camouflage pattern may be defined by the absence of
elements of the first and second sizes. Alternatively, the camouflage
pattern may be defined by the presence of further elements.
The density of the background printed matter and the density of the
cancellation term may vary together in a nonlinear fashion across at least
some of the bands. The density of the background printed matter and the
density of the cancellation term may vary together in a logarithmic manner
across at least some of the plurality of bands. The density of the
background printed matter and the density of the cancellation term along
each edge of each band may be substantially the same as the density of the
background printed matter and the density of the cancellation term along
the edge of the adjacent band, respectively.
A plurality of cancellation terms may be printed on the surface, with at
least some of the cancellation terms being printed over more than one of
the plurality of bands. The cancellation term may consist of a plurality
of letters, each of which is approximately two bands in height. The
plurality of cancellation terms and the plurality of bands may vary in
height.
The color of the background printed matter and the color of the
cancellation term may vary together over the surface. The upper portion of
the security document may be printed with a first color and the lower
portion of the security document may be printed with a second color. The
color transition area in the central portion of the security document may
be printed in both colors at a relatively low density.
The screen angle of the pattern of elements in the central portion printed
with the first color may differ from the screen angle of the pattern of
elements in the central portion printed with the second color, thereby
facilitating a smooth transition between colors.
Accordingly, it is an object of the present invention to provide an
improved security document in which the tone of the document varies over
at least a portion of the document surface such that a cancellation term
that is not readily apparent on the document appears on copies of the
document; to provide such a document in which at least a portion of the
document surface may be divided into a plurality of generally parallel
bands, with the tone of the document varying in different manners in each
of the bands; to provide such a document in which the tone of the
background printed matter and the tone of the cancellation term are
similar, but not equal; and to provide such a document in which the
letters making up the cancellation term extend over more than one band.
Other objects and advantages of the invention will be drawings and the
following description, the accompanying drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a check according to the present invention as it would
appear to a casual observer;
FIG. 2 is an enlarged portion of the check of FIG. 1;
FIG. 3 is an illustration of two different areas on the surface of the
document, greatly enlarged;
FIG. 4 illustrates the appearance of a reproduction of the document of FIG.
1 obtained on a color copier or desk top publishing system;
FIG. 5 is a drawing, similar to FIG. 4, illustrating the appearance of a
reproduction obtained on a color copier or desk top publishing system at
different control settings;
FIG. 6 is drawing, similar to FIG. 4, illustrating the appearance of a
reproduction obtained on a color copier or desk top publishing system at
other control settings;
FIG. 7 is as illustration of an alternate embodiment of the present
invention;
FIG. 8 is an illustration of another embodiment of the present invention;
FIG. 9 is an illustration of an alternate embodiment of . the present
invention;
FIG. 10 is an illustration of another embodiment of present invention;
FIGS. 11, 12 and 13 illustrate another embodiment of the present invention;
and
FIG. 14 illustrates graphically the changes in image density of yet another
embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 illustrates a check 10 made according to the present invention, as
seen by a casual observer, with a lighter tone area, first part 20, and a
darker tone area, second part 22. The lighter appearance of first part 20
is due to smaller element size which results in a smaller percentage of
the area of first part 20 that is covered with ink compared to second part
22. The second part 22 is shown as defining a complete border around first
part 20. However, it may form only a partial border. It will be
appreciated that the first part 20 may be darker than the second part 22,
if desired.
FIG. 2 is a detailed illustration of a portion of check 10. FIG. 2 shows
sections of first part 20 and second part 22. First part 20 contains
elements of first background printed matter 30 and first warning phrase or
cancellation term 32. The elements of first background matter 30 are
illustrated as being smaller than those of first cancellation term 32, but
they could be larger, as well.
Second part 22 has elements of second background printed matter 34 and
second cancellation term 36. The elements of second background printed
matter 34 are represented as being smaller than those of second
cancellation term 36; alternatively, they could be larger, however. The
elements of second background printed matter 34 are represented as being
larger than those of first background printed matter 30, and the elements
of second cancellation term 36 are shown as being larger than those of
first cancellation term 32. However, they could be smaller.
The frequencies of the elements in the first and second background printed
matter may be the same or they may be different. Similarly, the
frequencies of the elements of the first and second background terms may
be the same or different. For instance, one useful combination would be
130 lines per inch at 10% and 65 lines per inch at 15% in the first part,
and 130 lines per inch at 20% and 65 lines per inch at 25% in the second
part. Another useful combination might be 130 lines per inch at 10% and 65
lines per inch at 15% for the first part, and 120 lines per inch at 20%
and 60 lines per inch at 25% in the second part.
Phantom dotted lines 40 do not actually appear on the check. They have been
used merely to show the edges of the camouflage image 38. The camouflage
image may be defined by the absence of the elements of the first and
second background printed matter and first and second cancellation terms.
It may also be defined by the presence of elements of a larger or smaller
size than the background elements.
FIG. 3 shows an enlarged view of an area of the first part 20 and second
part 22 on a different security document. The camouflage image 38 consists
of wavy lines on the illustrated document. The elements of the first
background printed matter 30 are smaller than the elements of first
cancellation term 32. The elements of second background printed matter 34
are smaller than the elements of second cancellation term 36, but larger
than the elements of first background printed matter 30. The elements of
second cancellation term 36 are larger than the elements of first
cancellation term 32.
The frequency of the elements of first background printed matter 30 is the
same as the frequency of second background printed matter 34. The
frequency of the elements of first and second cancellation terms 32 and 36
is the same, and it is less than that of first and second background
printed matter 30 and 34.
The relationship between the size and frequency of the elements explains
the difference in the appearance of the two parts. First part 20 appears
to be lighter in tone than second part 22 because there is a lower
percentage of the document surface covered with ink in relation to the
total area of the document surface in first part 20; first part 20 is
therefore of a lighter tone than second part 22. This is advantageous in
that if a copier is adjusted to obscure or eliminate a cancellation term
in first part 20 of a copy, the cancellation term in the second part 22
will appear on the reproduced copy. Similarly, if the copier is adjusted
to obscure or eliminate the cancellation term in the second part 22 of the
copy, the cancellation term in first part 20 will appear on the reproduced
copy.
It should be appreciated that the tone of an area of a document, that is
the darkness or lightness of the document as it appears to the eye of an
observer, is not a function of only density of the halftone printing
elements. It is true, however, that with a halftone screen of a given
number of lines per unit length, a greater density which results from
larger halftone dots will produce a darker tone. It has been found,
however, that an area having large, widely spaced dots will appear lighter
in tone than another area having smaller, more closely spaced dots, even
though the amount of document surface covered by ink per unit area is the
same in each instance.
FIGS. 4, 5, and 6 represent the results of various attempts to copy the
check 10 of FIGS. 1 and 2 on a color copier. In FIG. 4, when the copier is
adjusted to obscure cancellation term 44 in second part 22, cancellation
term 42 in first part 20 appears clearly on the reproduced copy.
In FIG. 5, if the copier is adjusted to lighten the copy to eliminate
cancellation term 42 in first part 20, the adjustment produces a copy in
which cancellation term 44 in second part 22 is clearly visible on the
reproduced copy. Finally, in FIG. 6, when the copier is adjusted to
obscure cancellation term 42 in first part 20 of the reproduced copy,
cancellation term 44 in second part 22 is readily apparent on the
reproduced copy.
FIG. 7 shows an alternative embodiment of the present invention. The check
50 contains elements of background printed matter, elements of a
cancellation term, and a camouflage pattern as illustrated above in
respect to FIGS. 1-6. The tone of the elements varies across the face of
the check 50. It could decrease from left to right as shown. This may be
accomplished by varying the size of the halftone elements, their spacing,
or both, across the face of the check 50. Other variations are possible.
FIG. 8 illustrates diagrammatically yet another embodiment of the present
invention. In this embodiment, the frequencies of the elements of the
background printed matter and the cancellation terms remain the same,
while the size of the elements is varied across the document. This is
called a graded screen. For example, the frequency might be 130 and 65
lines per inch for the background printed matter and the cancellation
term, respectively. The size of the elements of the background printed
matter may vary across the document from 50% of the area covered to 5%,
and the cancellation term may vary across the document from 60% to 7%. In
the illustrated document, the highest percentages of coverage are at the
top of the document. These percentages are gradually reduced toward the
bottom of the document. The illustrated document shows this change in
coverage percentages as occurring in steps, producing bands of slightly
different tone. If desired, however, the size of the dots may be
continuously varied over the document surface. Regardless of the manner in
which the dot size of the background printed matter and the dot size of
the cancellation term are varied, the selection of dot sizes for a given
area on the document is made such that they provide substantially equal
tone.
The address area 60 and the amount area 62 are made of halftone elements
which are substantially the same spacing as the background elements. These
areas may contain the camouflage pattern or it may be omitted. The address
area 60 and the amount area 62 are readable by image scanners. FIG. 8 also
shows a quality control target 69 printed on the surface of the check. The
quality control target comprises a high density area 70, a low density
area 72, and an intermediate density area 74. Warning bands 76 of high
density printing may be positioned at the top and bottom of the check 50
as shown. The low density printing may be used for portions such as the
address and amount areas 60 and 62. Intermediate targets 75 may be
provided in obscure areas of the form and printed without the camouflage
pattern.
FIG. 9 illustrates diagrammatically yet another embodiment of the present
invention, with parts of the document corresponding to those of FIG. 8
being labeled with like reference numerals. In the embodiment of FIG. 9,
the frequencies of the elements of the background printed matter and the
cancellation terms are constant, while the size of the elements is varied
across the document. In contrast to the embodiment of FIG. 8, however, the
highest percentages of coverage by screen elements occurs at both the top
and bottom of the document. The percentages are gradually reduced toward a
central band 80 of generally uniform tone. As with FIG. 8, FIG. 9 shows
the changes in percentage coverage occurring in steps, producing bands of
slightly different tone. If desired, however, the size of the dots may be
continuously varied over the document surface. Once again, the selection
of dot sizes for given areas on the document is made such that they
provide substantially equal tone.
FIG. 10 illustrates diagrammatically a further embodiment of the present
invention, with parts of the document corresponding to those of FIG. 8
being labeled with like reference numerals. In the embodiment of FIG. 10,
the frequencies of the elements of the background printed matter and the
cancellation terms are constant, while the size of the elements is varied
across the document. In contrast to the embodiment of FIG. 9, the
embodiment of FIG. 10 does not include a central band of generally uniform
tone. Rather the percentage of coverage by the screen elements gradually
decreases from the top and bottom of the document to the middle of the
document. As with the other embodiments, the selection of dot sizes is
made such that the background printed matter and the adjacent portions of
the cancellation terms are of substantially equal tone.
It should be understood that the phrase "cancellation term" is intended to
include not only words such as the word "VOID" shown in the drawings, but
also words and phrases which simply make evident to an observer that the
document being inspected is a copy of the original document. Such phrases
as "PHOTOCOPY", "COPY", and "DUPLICATE" may be used for this purpose. Also
intended to be included within the phrase "cancellation term" are words or
symbols which may signify to the individual making the copy that the
original document is authentic.
The present invention may be incorporated in a number of different security
documents of varying design. FIGS. 11-13 illustrate yet another embodiment
of the present invention. FIG. 11 shows the improved security document 70
with all alphanumeric printed matter removed, leaving only the background
printed matter, the cancellation term, and the camouflage pattern printed
on the substrate 72 having a surface for carrying indicia. The background
printed matter consists of a pattern of elements of a first size and a
first frequency such that the background printed matter is printed at a
first density perceived by an observer as a first tone. The cancellation
term consists of a pattern of elements of a second size and a second
frequency such that the cancellation term is printed at a second density
perceived by an observer as a second tone. As with the embodiments
previously discussed, elements of one of the first size or the second size
are sufficiently small such that they are not reproduced by a color copier
at a particular copier setting, and elements of the other of the first
size or the second size are sufficiently large such that they are
reproduced by the color copier at the particular copier setting. As a
consequence, a copy of the security document made on a color copier
displays the cancellation term.
In this embodiment, the security document surface is divisible into a
plurality of bands extending across the surface. This is more clearly
shown in FIGS. 12 and 13, with the bands being designated by reference
numerals 74 through 82. The document is illustrated with the entire
surface divided into bands, but it should be understood that only a
portion of the surface may be divided in this manner, if desired.
Furthermore, the document is illustrated with the bands extending across
the entire width of the document. If desired, however, other arrangements,
such as non-parallel bands, extending radially outward from a common
point, may be utilized. FIG. 12 illustrates the document of FIG. 11 as it
would appear without the camouflage image, while FIG. 13 graphically
depicts the change in densities of the areas printed with the first and
second size elements. Note that the sizes of the elements of the first and
second sizes vary across each of the bands. As a consequence, the density
of the background printed matter and the density of the cancellation term
vary together across each of the bands on the surface in a direction
generally normal to the bands. By this arrangement, copying the security
document without the cancellation term being apparent on at least some
portion of the copy is impeded. It should be appreciated that in some
instances the size of the elements of the first and second sizes will vary
across less than all of the bands.
The camouflage pattern, defined by the absence of the elements of the first
and second sizes in a pattern simulating blocks, disguises the
cancellation term quite well. The degree to which this disguise is
successful can be easily seen by comparing FIGS. 11 and 12.
It should be appreciated that any of a wide variety of camouflage images
may be utilized in this fashion to disguise the cancellation terms on a
security document according to the present invention. For a camouflage to
be effective, the camouflage image usually occupies about 50% of the
document surface area. A properly configured camouflage image becomes the
dominant image in the eye of the casual observer. Although a camouflage
pattern defined by the absence of elements is shown in FIG. 11, it will be
understood that a camouflage pattern may also be defined by the presence
of further elements.
As is apparent from FIG. 12, the cancellation term consists of a plurality
of letters, each of which is approximately two bands in height. Actually,
a plurality of cancellation terms are printed, with each cancellation term
being printed over an associated pair of the plurality of bands.
Specifically, the cancellation term consists of the word "VOID" repeated
numerous times along each of the bands 74-82. Although the x-axis of FIG.
13 is not drawn to scale, it will be appreciated that the plurality of
cancellation terms and the plurality of bands 74-82 vary in height. Band
79 is generally twice as high as the other bands.
A careful inspection of FIG. 12 reveals that while the tone of the
background printed matter and the tone of the cancellation term are
generally the same at each point on the document, still some differences
between the tone of the background printed matter and the tone of the
cancellation term do exist. The density of each portion of the surface
printed with those elements which are sufficiently large such that they
are reproduced by the color copier at the particular copier setting is
greater than the density of adjacent portions of the surface printed with
elements which are sufficiently small such that they are not reproduced by
a color copier at the particular copier setting. These differences in tone
and density enhance the ability of the security document of the present
invention to impede copying without the cancellation term being apparent
on a least some portion of the copy. Even with these differences in
density and tone, however, the cancellation terms are sufficiently
obscured by the camouflage image so as not to be apparent to the eye of a
casual observer. It will be appreciated, however, that if desired the
densities may be selected such that the tone of the background printed
matter and the tone of the cancellation term are the same at each point on
the document.
As will be noted from a review of FIG. 13, the density of the background
printed matter and the density of the cancellation term vary together
linearly across each of the plurality of bands. In some cases, however,
the density of the background printed matter and the density of the
cancellation term will vary together only across some of the plurality of
bands. In the illustrated document, the background printed matter is
printed with a 130 line per inch, halftone dot screen, and the
cancellation term is printed with a 65 line per inch halftone dot screen.
The density of the cancellation term in band 74 is 100%, meaning full ink
coverage at the top of the band, and drops to 70% at the bottom of the
band. Similarly, the density of the background printed matter in band 74
is 70% at the top of the band, and drops to 42% at the bottom of the band.
Note that the density of the cancellation term in band 75 is 70% at the
top of the band and drops to 55% at the bottom of the band. Similarly, the
density of the background printed matter in band 75 is 42% at the top of
the band, and drops to 36% at the bottom of the band. The density of the
background printed matter and the density of the cancellation term along
each edge of each of the bands 74 through 82 are substantially the same as
the density of the background printed matter and the density of the
cancellation term along the edges of the adjacent bands, respectively. As
a consequence, the transition from one band to the next is accomplished in
a manner that is not readily apparent to a casual observer.
The density of the security document may be varied in other ways. The
density of the background printed matter and the density of the
cancellation term vary together in a non-linear fashion across at least
some of the bands. Reference is made to FIG. 14, which illustrates the
density changes in the background printed matter and the cancellation
terms of a security document having eight bands 83-90. Band 83 extends
across the top edge of the document and band 90 extends across the bottom
edge of the document. In this example, the heights of the bands for a
document which is the size of a typical check are as follows.
______________________________________
Band Height (inches)
______________________________________
83 .175
84 .200
85 .450
86 .475
87 .500
88 .450
89 .225
90 .211
______________________________________
In this example, the background printed matter is printed with a 130 line
per inch, halftone dot screen at a 45.degree. screen angle, and the
cancellation term is printed with a 65 line per inch, halftone dot screen
at a 45.degree. screen angle. The density values are as follows.
______________________________________
Band
num- Cancellation term Background printed matter
ber Taper Start Stop Direct
Taper Start
Stop Direct
______________________________________
83 LIN 55 70 90 LIN 36 42 90
84 LOG 35 55 90 LOG 25 36 90
85 LOG 35 20 270 LOG 25 14 270
86 LOG 20 12 270 LOG 14 7 270
87 LIN 12 7 270 LIN 7 5 270
88 LIN 11 7 90 LIN 6 5 90
89 LOG 17 11 90 LOG 11 6 90
90 LOG 17 26 270 LOG 11 16 270
______________________________________
In this table, the abbreviations used are as follows.
"Taper" indicates the type of change of the graduated screen between the
start and the stop values. LIN indicates an equal change for equal
distance increments between the start and stop boundaries. LOG indicates a
more rapid change for equal distance increments closer to the start
boundary and becoming progressively less closer to the stop boundary. It
should be noted that the density of the background printed matter and the
density of the cancellation term vary together in a logarithmic manner
across at least some of the plurality of bands.
"Start" is the screen percentage selected to start the band. It may be at
the top or bottom of the band depending on the direction of taper. "Stop"
is the screen percentage selected to end the band. It may be at the top or
bottom of the band depending on the direction of taper.
"Direct" is the direction of change in dot sizes between the start and stop
boundaries. A notation of 270 means that the values change from the start
value at the top of the band to the stop value at the bottom of the band.
A notation of 90 means that the values change form the start value at the
bottom of the band to the stop value at the top of the band.
If desired, a security document according to the present invention may be
printed in more than one color ink. It has been found to be desirable to
print the upper or lower bands of a document with a blue ink, and the
remaining bands with a green ink. With a document in which the tone
becomes progressively lighter toward the center portion of the document,
the transition from blue to green is very subtle, and the color of the
background printed matter and the color of the cancellation term appear to
vary together over the surface. This technique permits the printing of a
document in which a gradual blending of the colors is approximated.
To facilitate the blending of colors, overlapping of areas printed with the
two colors is accomplished. As an example, if the upper half of a document
is printed with blue ink and the lower half of the document is printed
with green ink, the bottom band of the upper half of the document may also
be printed with green ink. Preferably, this bottom band is printed in
green ink only with smaller elements, and the screen angle of these
smaller elements differs from the screen angle of the elements printed in
blue ink. For example, elements printed in blue ink may have a screen
angle of 45.degree., whereas elements printed in green ink may have a
screen angle of 90.degree.. A similar arrangement is provided for the
upper band of the bottom half of the document. By this technique, the blue
and green elements are, for the most part, not printed on top of each
other, and both colors are visible.
It will be appreciated that differing arrangements may be utilized within
the scope of the present invention to cause of the tone of the background
printed matter and the tone of the cancellation term or terms to vary
across at least some of the bands. For example, in another embodiment the
sizes of the elements of the first and second sizes may vary across each
of the bands and the frequencies of the elements of the first and second
frequency may vary across each of the bands. In this embodiment, the
density of the background printed matter and the density of the
cancellation term vary together across each of the bands on the surface in
a direction generally normal to the bands. In yet another embodiment, only
the frequencies of the elements of the first and the second frequency
varying across at least some of the bands such that the density of the
background printed matter and the density of the cancellation term vary
together across at least some of the bands on the surface in a direction
generally normal to the bands.
It will be further appreciated that it may be desirable in some instances
to provide an area of the document of the present invention with
background printed matter and cancellation terms that do not vary in tone.
This may be the case, where a uniformly light tone is desired to
facilitate reading information that is to be printed later in this area.
Further, it may be desirable in some instances to provide an area of the
document without any of the larger sized elements that make up either the
background printed matter or the cancellation terms. This may be the case
where it is desired to print machine scannable characters in this area,
and the larger elements may impede character recognition.
Having described the improved security document of the present invention in
detail and by reference to different embodiments thereof, it will be
apparent that certain modifications and variations are possible without
departing from the scope of the invention defined in the appended claims.
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